I want to make animation in RF, which I will import it later in Maya for render.I need to drop some object into water and it need to go down all the way to the bottom. But how to do that? I know for Daemons, gravity for example, but how to use hybrido to make bubbles with object falling and others stuffs to be my scene realistic?

RF10 comes with a number of ready-made projects that can be found in the "learn" section of the open projects window. The scene "Hybrido_Bubbles" is the one for you. It shows a rocket falling into a closed hybrido tank. You just have to add a mesh for the hybrido domain and a particle mesh for the bubbles.